This disclosure relates generally to a catheter system for connecting adjacent blood vessels, e.g, an artery and an adjacent vein to adapt the vein for arterial blood flow. More particularly the invention concerns a system of two catheters with mating, magnetic tips for creating openings in the artery wall and vein wall to form a fistula connecting the blood vessels. Further, the disclosure relates to a ratchetable catheter having a wide arc of potential space through which a piercing tool may be fired from a first blood vessel to a second blood vessel.
A catheter apparatus and method for arterializing a section of a vein to bypass a clogged artery are shown in U.S. Pat. No. 6,464,665, which is hereby incorporated by reference. The method is used to bypass a stenosis in the artery that obstructs blood flow in a portion of the artery. If the obstructed portion of the artery can be bypassed, blood flow will be restored downstream from the stenosis. A vein running alongside the artery in the obstructed portion of the artery can be used for the bypass.
The catheter apparatus includes one catheter for inserting into the artery and another catheter for inserting into the adjacent vein. The physician maneuvers the tips of both catheters to coincident positions within each blood vessel adjacent one end of the obstructed portion of the artery. The physician then creates an opening from the inside of one blood vessel through the vessel wall and then through the wall of the other blood vessel.
An issue arises in co-locating the openings in the two blood vessels and holding the vessel walls in place to ensure that a channel will be created between the vessels so that blood will flow from one vessel to the other. A further issue arises in aiming and maintaining the position of the catheters inside the vessels. In particular, veins often have diameters much larger than arteries, making hitting a smaller artery from a larger vein difficult. Additionally, larger veins often allow a catheter too much freedom of movement inside the vein.